Acute effect of nitroglycerin on haemodynamics of angina pectoris

Hemodynamic effects of molsidomine at rest and during submaximal and maximal exercise in patients with coronary artery disease limited by exertional angina pectoris

To analyze the mechanisms of action of molsidomine, a new antianginal drug, 10 patients with coronary artery disease and exertional angina pectoris were studied. Hemodynamic measurements were made at rest, during submaximal exercise and during angina-limited exercise before and 1 hour after intravenous administration of 2 mg of molsidomine. When angina pectoris was prevented after the drug was given (6 of 10 patients), the exercise intensity was increased until the recurrence of angina (3 patients) or until exhaustion (3 patients), and hemodynamic data were recorded at this higher exercise capacity. At rest and during submaximal exercise, molsidomine increased heart rate and decreased cardiac output and mean systemic and pulmonary arterial pressures. The prevention of angina pectoris was attended by lower mean systemic and pulmonary arterial pressures and pressure-rate product; cardiac output and heart rate were unchanged. The greater exercise capacity (+26 percent) after molsidomine was attended by increases in maximal cardiac output (+19 percent) and in arteriovenous oxygen difference (+6 percent); the maximal pressure-rate product was unchanged and systemic vascular resistance was lower. The mechanisms of action of molsidomine are very similar to those of nitrates and imply a decrease in venous and arterial tone. Molsidomine deserves further study in patients with angina or congestive heart failure.

The effect of nitroglycerin upon pulmonary and left atrial pressures in patients with mitral stenosis

In all nine patients studied with mitral stenosis and no evidence of left ventricular failure, nitroglycerin caused a decrease in pulmonary arterial, left atrial, and left ventricular pressures and pulmonary vascular resistance. The decrease in left atrial pressure was attributable to the combination of a reduction in left ventricular filling pressure and a reduction in mitral valve gradient. While there was no significant mean change in heart rate, cardiac index, or mitral valve flow, there was a significant correlation between a decrease in each of these determinants of mitral valve gradient and the observed decline in left atrial pressure in individual patients. However, even those patients who had an increase in heart rate or cardiac output, either of which normally aggravates pulmonary congestion in mitral stenosis, had a decrease in their pulmonary and left atrial pressures in response to TNG. It is likely that nitroglycerin reduced pulmonary and left atrial pressures by either (1) systemic venous dilatation, causing a reduction in right heart filling and pulmonary blood volume, or (2) pulmonary arteriolar and venous dilatation, causing a decrease in pulmonary vascular resistance and an increase in pulmonary vascular compliance. Because of the efficacy of TNG in lowering pulmonary and left atrial pressures in this study, TNG may prove useful in the clinical management of symptomatic pulmonary congestion in mitral stenosis.

Improvement in left ventricular wall motion following nitroglycerin

Coronary artery disease patients frequently have left ventricular wall motion abnormalities. Though nitroglycerin is commonly used in ischemic heart disease, its effects on wall motion abnormalities is unknown. In this study we have evaluated the effects of nitroglycerin on wall motion abnormalities and on ejection fraction in 25 patients. Sixteen had coronary artery disease (greater than 70% luminal narrowing). Six had no evidence of heart disease and three had congestive cardiomyopathies with normal coronary arteries. Left ventricular angiography was performed prior to and six minutes after administration of 0.4 mg of sublingual nitroglycerin. Twelve of the 16 coronary artery disease patients had wall motion abnormalities, and in seven of these, segmental wall motion improved after nitroglycerin. In five, all motion did not change. The initial heart rate, left ventricular systolic and end-diastolic pressure, and left ventricular end-diastolic volumes were not different for those whose wall motion improved versus those whose did not. The increase in the former and fall in the latter three hemodynamic parameters were significant (P less than 0.01) and similar for the two groups. In those whose wall motion abnormalities improved after nitroglycerin, ejection fraction (mean plus or minus se) increased significantly (P less than 0.05), from 0.47 plus or minus 0.025 to 0.62 plus or minus 0.046. In those without improvement, the ejection fraction went from 0.55 plus or minus 0.056 to 0.58 plus or minus 0.051 (NS). Three patients with congestive cardiomyopathy showed no improvement in ventricular wall motion or ejection fraction after nitroglycerin. Left ventricular wall motion abnormalities and ejection fraction improved in some coronary artery disease patients following nitroglycerin. The mechanism for this is unknown; however, ventriculography before and after nitroglycerin may be of potential usefulness for identifying areas of reversible wall motion abnormalities.

Hemodynamic effects of nitroglycerin, propranolol, and their combination in coronary heart disease

The hemodynamic effects of 10 mg of propranolol given intravenously (iv) were studied in 10 patients (group I) with coronary heart disease (CHD). These results were compared with the hemodynamic effects in a similar group of the nine (CHD) patients (group II) who were studied after administration of 0.6 mg of nitroglycerin and then after receiving 10 mg of propranolol iv with a second 0.6-mg dose of nitroglycerin. Measurements were obtained at rest and during exercise: before treatment, after nitroglycerin alone, after propranolol alone, and after nitroglycerin-propranolol in combination. Pretreatment exercise showed a 125% increase in mean pulmonary artery pressure (PAP) to 43 mm Hg and a 163% increase in left ventricular end-diastolic pressure (LVEDP) to 29 mm Hg. Nitroglycerin decreased PAP (–45%) and LVEDP (–66%); as did nitroglycerin-propranolol: PAP (–33%) and LVEDP (–38%). Nitroglycerin reduced tension-time index (TTI) –21%, and increased cardiac index (CI) +17%, heart rate (HR) +10%, left ventricular work index (LVWI) +11%, and left ventricular dp/dt (LV dp/dt) +22%. By contrast, nitroglycerin-propranolol reduced LVWI –14%, LV dp/dt –30%, TTI – 15%, and HR – 13% but did not significantly alter CI from pretreatment.

Propranolol increased PAP to 40 mm Hg, did not change LVEDP at 29 mm Hg and decreased stroke index (SI) 16%. Nitroglycerin-propranolol diminished PA and LVED pressure and increased SI 14%. Effects of propranolol alone and of nitroglycerin-propranolol on HR, TTI, and LV dp/dt were not significantly different.

Nitroglycerin-propranolol appears to have important advantages over nitroglycerin or propranolol alone. A reduction in HR, TTI, and LV dp/dt, determinants of myocardial oxygen consumption, concurrent with improved left ventricular function, demonstrates a beneficial synergistic hemodynamic action for nitroglycerin combined with propranolol.

Intra-hepatic vascular response to sodium nitrite

1. In the perfused liver of the dog, sodium nitrite produced vasoconstriction in the hepatic arterial bed and, particularly, in the portal venous vascular bed.2. These effects on the hepatic vasculature may account in part for the reduction of venous return and diminution in cardiac output recorded by other workers, and may therefore be a factor in the clinical efficacy of the nitrites in angina pectoris.